In the Navigation Pane, click Grammar, and then click Phonemes.
In the Phonemes pane, click the phoneme you will delete
Do one of the following:
On the Standard
toolbar, click .
On the Edit menu, click Delete Phoneme.
Right-click, and then select Delete Selected Phoneme.
The Delete Phoneme warning box appears and asks if want to continue with the deletion.
If you are sure you want to delete the phoneme specified in the warning box, click Delete.
The specified phoneme is deleted.
Phonemes are used by natural classes and environments.